Split port info. Pics, links, and more!

Discussion in 'Tech Articles, How-To's & Write Ups' started by jwhisl, Jan 10, 2014.

  1. jwhisl

    jwhisl Active Member

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    Dec 28, 2012
    Ok so I just completed my split port swap on a 95 3.8. There are several write-ups around the web on how to do the swap and parts that are needed but I found there was always information missing from those. First off let me say that if you only have one vehicle to drive, I really don't recommend trying the swap. Also it's going to cost anywhere from $500 to $1100 for all the parts. More if you are paying someone to install everything. I had access to a parts car to pull a majority of the parts I needed and I ordered the heads refurbished from ebay fully assembled for $300 J&C Enterprises
    Now here is a list of things you will need:
    - Upper and lower intake from 99-04 (99-00 are easier to deal with since they don't have the IMRC*)
    - 99-04 Split Port heads
    - 99-04 throttle body and throttle cable
    - 99-04 cruise control module and cable, if you want cruise control
    - 99-04 injectors
    - 99-04 heater tubing for the lower intake
    - 99-04 upper radiator hose
    - 99-04 air intake tube with mass air
    - 99-04 vacuum lines and fuel rails
    - 99-04 injector harness
    - 99-04 egr system
    - 99-04 heater hoses
    *Intake Manifold Runner Control- individual butterflies in the secondary intake runners that are controlled by the ecu

    Now then if you decide to go ahead with this swap you will need to be good with wiring and soldering. You will need to combine both fuel rails since 94-98 mustangs use return style fuel systems. That is unless you want to change out the entire fuel system from the 99-04. Here is a great write up by a member here http://www.sn95forums.com/showthread.php?62609-split-port-swap-fuel-rail-how-to I used weather head efi fuel line purchased from my local auto parts store (Napa auto parts) I also made the line between the fuel pressure regulator and passenger side fuel rails a bit longer so I would have room to work once everything was bolted on. After you have combined the two sets of rails you will have two spots for fuel pressure regulators. I just left the regulator in place from the 99-04 but you can make a block off plate like the one in the link if you want. The IMRC butterflies will need to be removed from the lower intake. Just drill out the screws that hold them in because the screws are not designed to com back out.
    And on the car[​IMG]

    Now on to the wiring. There are a number of differences in the wiring harnesses and no they aren't interchangeable. You will need to change all the injector plugs as well as extend them since the 94-98 wiring won't reach the front 4 injectors. You will also need to extend/change the plug for the coil pack, throttle position sensor, oil pressure sensor, and the sensor by the bottom of the water pump on the passenger side. I decided to use my coil pack from the 95 and unwrapped all the wiring back to the point where the harness splits for all the injectors. That will give you an extra 8 inches or so of wiring bu you will still need to extend the plug to reach around to the upper intake where it mounts. If you keep the older coil pack you can use 99-00 plug wires. Make sure to heat shrink and wrap all the wiring back up. You can buy injector adapters from late model restoration here but be aware that they will hit the upper intake if you don't have an intake spacer. It's really just easier to solder on the correct plugs since you will be extending the wires anyways.

    You may notice in my pictures that there is no place for the temperature sensors. I failed to notice that tidbit until I reassembled the engine. Depending on which lower intake you get it will need to be drilled and tapped for the two sensors. The sensor with the prong is for the gauge and the other is for the ecu.

    Also you might as well delete the egr since you are going to have the engine that far apart I took the easy way out and made my own block off for the intake and smashed to tube closed by the exhaust manifold.

    I was able to reuse my cold air intake tubing by cutting a little off the end by the throttle body. That will save a little bit of money.

    So now you have all the wiring done and your engine is back together. Yes you can technically start it and drive it without a tune but DON'T! Your car will run extremely rich/flood out and will not restart until the excess fuel dissipates! If you can't afford a tune right away you can use a mass air sensor from a 94-95 gt in the your stock v6 mass air housing. It will help the ecu deal with the larger injectors but you will still have issues restarting the car after it's shut off.


    In retrospect it probably would have been cheaper and easier to swap a 5.0 into the car, not to mention quicker. This is a lot of work to do only to gain around 50hp at the flywheel.

    Anything I may have forgot feel free to ad to this thread or I can edit this post.